Grid support for mercury arc rectifier



United States Patent one 3,252,041 Patented May 17, 1966 3,252,041 GRIDSUPPORT FOR MERCURY ARC RECTIFIER Harold Ernest Aldworth, Shalford,Guildford, and Zygmunt Sawko, Stafford, England, assignors to TheEnglish Electric Company Limited, Strand, London, England, a Britishcompany Filed Oct. 5, 1962, Ser. No. 228,689 Claims priority,application Great Britain, Oct. 11, 1961, 36,480/61 4 Claims. (Cl.313-265) This invention relates to mercury arc rectifiers and isconcerned with .the problem of supporting and cooling the grid.

It is an object of the present invention to provide a grid supportstructure which is contained entirely within the valve envelope and isnot built into it by any metal joining process.

According to the invention, a mercury arc rectifier includes an annularelectro-conductive envelope mounted between axially spaced insulatingwalls and agrid supported from within the envelope through mountingmeans which also serve to provide an electrical connection between theenvelope and the grid.

According to a preferred feature of the invention, the envelope extendsoutwardly beyond the periphery of the insulating walls and the mountingmeans includes a generally axially extending annular electro-conductivesupport member carrying at its lower end an annular grid and having atits upper end a flange portion which extends outwardly into the envelopeand which is supported within the envelope by a plurality of springmembers which also provide an electrical connection between the envelopeand the flange portion.

According to another preferred feature of the invention the annularsupport member is hollow and provides a first hollow portion at saidlower end for the reception of liquid mercury or the like and a secondhollow portion constituted by said flange portion and in communication.with the first hollow portion, the arrangement being such that heat istransferable from the grid to the envelope by phase change of themercury which evaporates in the first hollow portion, ascends to andcondenses in the second hollow portion, and returns to the first hollowportion by the action of gravity.

Further preferred features of the invention will appear from thefollowing description with reference to the accompanying drawing whereinis shown one arrangement of mercury arc rectifier according to theinvention.

Referring now to the drawing, the mercury arc rectifier includes a valveenvelope generally indicated at and mounted between axially spacedceramic insulating walls 11. An annular grid 12 is secured at a joint 13to a. grid support member generally indicated at 14. The grid supportmember 14 comprises a vertically disposed hollow tubular portion 15 buttwelded at the upper end thereof to an outwardly extending hollow flangeportion 16. The hollow construction of the support member 14 'providesan annular enclosure 17 containing a mercury pool 18. A tubular shield19 extends upwardly from the support member 14.

The valve envelope 10 consists of welded segments 20, 21, 22 and 23arranged to provide an annularly shaped internal recess 24 and twore-entrant annular spaces 25 and 26. The flange portion 16 of thesupport member 14 is located and resiliently supported within the recess24 by means of nimonic alloy strip springs 27 which also provide thenecessary electrical connection to the grid. A baffle structure 28surrounds the valve envelope 10 and is separated therefrom byelectro-conductive nimonic alloy strip springs 29. The baffle structure28 provides an oil flow path indicated by the arrowssuch that oil may becaused to flow over the surfaces of the valve envelope 10 in a tortuouspath. A resilient annular member 30 attached to an annular ceramic outerwall 31 exerts radial pressure on the baflle structure 28 and acts as abarrier to oil tending to by-pass the path shown by the arrows. Theannular member 30 is provided with axial slits (-not shown) to giveflexibility. A slight oil by-pass is. therefore unavoidable.

Heat flows from the grid across the joint 13 and causes boiling in themercury pool 18. The vapour so produced ascends to the flange portion16, condenses, and returns to the pool 18 by gravitational action. Heatis transferred from the flange portion -16 to the valve envelope 10 byradiation and thence by convection to oil coolant flowing over the wallsof the envelope in the path indicated by the arrows.

What we claim as our invention and desire to secure .by Letters Patentis:

1. A mercury arc rectifier having, in combination, an envelope includingtwo coaxially disposed non-conducting tubular members spaced axiallyfrom each other by a conducting tubular member forming a tubular cavitybetween the two non-conducting members of larger cross section than thenon-conducting members, a grid member within the envelope having aflange portion projecting into, but spaced from, the cavity, andresilient mounting means within said cavity providing both a support forthe grid member and an electrical connection between the gridmember andthe tubular conducting member.

2. A mercury arc rectifier having, in combination, an envelope includingtwo coaxially disposed non-conducting tubular members spaced axiallyfrom each other by a conducting tubular member forming a tubular cavitybetween the two non-conducting members of larger cross section than thenon-conducting members, a grid member within the envelope having aflange portion projecting into, but spaced from, the cavity, and aplurality of generally U- shaped corrugated springs interposed betweenthe flange portion of the grid member and the inside faces of thetubular cavity providing both a support for the grid member and anelectrical connection between the grid member and the tubular conductingmember.

3. A mercury arc rectifier having, in combination, an envelope includingtwo coaxially disposed non-conducting tubular members spaced axiallyfrom each other by a conducting tubular member forming a tubular cavitybetween the two non-conducting members of larger cross section than thenon-conducting members, a grid member within the envelope having aflange portion projecting into, but spaced from, the cavity, andresilient mounting means within said cavity providing both a support forthe grid member and. an electrical connection between the grid memberand the tubularconducting member, the grid member having an annularcavity below the flange portion communicating directly with an annularcavity within the flange portion and which contains mercury or the likeso that, in operation, heat may be transferred from the grid member tothe flange member by phase change of the mercury or the like.

4. A mercury arc rectifier having, in combination, an envelope includingtwo coaxially disposed non-conducting tubular members spaced axiallyfrom each other by a conducting tubular member forming a tubular cavitybetween the two non-conducting members of larger cross section than thenon-conducting members, a grid member within the envelope having aflange portion projecting into, but spaced from, the cavity, resilientmounting means 3 within said cavity providing both a support for thegrid member and an electrical connection between the grid member and thetubular conducting member, the grid member having an annular cavitybelow the flange portion communicating directlyLWith an annular cavitywithin the flange portion and which contains mercury or the like sothat, .in operation, heatmay be transferred from the grid member to theflange member by phase change of the mercury or the like, a tubularconducting bafiiemember disposed around, but spaced from, the tubularconducting member so as.to-guide coolant over the tubular conductingmember, and Second resilient mounting means providing both a mountingfor the bafiie member and an electrical connection between the bafliemember and the tubular conducting member.

References Cited by the Examiner UNITED STATES PATENTS 2,873,954 2/1959Protze 313-24 X JOHN W. HUCKERT, Primqry EXaminer. GEORGE N. WESTBY,Examiner. L. ZALMAN, Assistant Examiner.

1. A MERCURY ARC RECTIFIER HAVING, IN COMBINATION, AN ENVELOPE INCLUDINGTWO COAXIALLY DISPOSED NON-CONDUCTING TUBULAR MEMBERS SPACED AXIALLYFROM EACH OTHER BY A CONDUCTING TUBULAR MEMBER FORMING A TUBULAR CAVITYBETWEEN THE TWO NON-CONDUCTING MEMBERS OF LARGER CROSS SECTION THAN THENON-CONDUCTING MEMBERS, A GRID MEMBER WITHIN THE ENVELOPE HAVING AFLANGE PORTION PROJECTING INTO, BUT SPACED FROM, THE CAVITY, ANDRESILIENT MOUNTING MEANS WITHIN SAID CAVITY PROVIDING BOTH A SUPPORT FORTHE GRID MEMBER AND AN ELECTRICAL CONNECTION BETWEEN THE GRID MEMBER ANDTHE TUBULAR CONDUCTING MEMBER.